Method of cutting bevel gear-wheels.



E. H. WlNGQViST. METHOD OF CUTTING BEVEIT GEAR WHEELS.

APPLICATION FILED NOV, 30, 1915.

i. ,281 735. Patented 0011.15, i918,

3 Quins-SHEET r.

E. H. WINGQVIST. METHOD OF CUTTING BEVEL GEAR WHEELS. APPLICATION FILED Nbv.30.19i5.

1,281,735. Patenmi 15, 518..

3 SHEETS*SHEET 2 Awa /2 x E. H. WINGQViST. METHOD OF CUTTING BEVEL GEAR WHEELS. APPLICATION FILED NOV. 30,1915.

i a'tenm Get 15,

ERIK HJALMAR WINGQVIST, OF GOTTENBOBG, SWEDEN, ASSIGNOR TO AKTI EBOLAGET SVENSKA KULLAGERFABRIKEN, 0F GOTTENBORG, SWEDEN, A CORPORATION OF SWEDEN.

METHOD OF CUTTING BEVEL GEAR-WHEELS.

Original application filed March 1?, 1915, Serial 6514364. "lil rided and this application filed November 30,

i915: seriaiivo. 64;??52.

To all whom it may concern:

ovisr, a citizen of the Kingdon'z of Sweden,

residing at Gottenborg, Sweden, have in-" vented new and useful Luproved Methods of Cutting Bevel Geardvheels, of which the following is a specification. This invention relates to an improved method of cutting bevel gear-wheels being a division of n y copending patent application Serial Number 14904 filed March 17, 1915.

As stated in said patent application a bevel gear-wheel is so formed that the bottom surfaces of the gaps between adjacent teeth lie on or approximately on the surface of a cone or other convergent pyramidal surface whose apex is situated beyond (measured from the gear-wheel) the apex of the normal pitcl1-co11e,'and the side surfaces of the teeth are formed on substantially customary theoretically correct lines convergent upon the apex of the normal pitch-cone. By this apparently insignificant modification it is possible, as will be described'below, to cut simultaneously both sides of a gap between adjacent teeth by means of a si 1 tool in one and. the same Working oper Thus the manufacture of bevel gear-wheels is rendered as simple and may be effected as readily as the manufacture of ordinary spur-wheels.

Preferably in a bevel gear-Wheel of this kind the bottom surface of a gap aforesaid is of uniform Width throughout itslength.

According to the present invention each gap between a pair of adjacent teeth of a bevel gear-wheel ofthe type described above is formed by traversing over a blank, during the cutting operation, an elongated tool having two cutting surfaces separatedby a third cutting surface, which is of uniform Width throughout its length andis situated v near to the line upon which the first two,

surfacesproduced converge. The-said tool is employed in such a manner that during the cutting operation both sides of the gap between the rteeth. .are simultaneously out,

While the stool (performs simultaneously a 1 cutting movementnin relation to the gear- Wheel blank, always maintaining such a position relatively to the said blank that the supposedtop linego f the said. tool passes y through the apex of L the pitoh cone or Specification of Letters Patent.

Patented Oct. 15, 1918.

touches a sphere, the center of situated in the said apex.

The invention will be more clearly understood from the following description read in conjunction with the accon'ipanying diawhich is 'graminatic drawings, in which Figures 1 and 2 illustrates a pltclrcone and generating-wheel in elevation and plan respectively for the purpose of explaining the principles underlying the usual formation of bevel gear-Wheels;

' 'F 3 to 5 diagrammatically illustrate various phases of construction of radial toothed bevel gear-wheels according to the present inventiom and Figs. 6 and 7 illustrate the formation of skew-toothed bevel gear vheels also made according to the present invention.

Figs. 1 and 2 illustratea so-called generating Wheel 1 supposed to be made of hard material and a cone 4: supposed to be made of plastic material. The generating wheel 1 is provided with teeth 9 in the form of three-sided pyramids, the tops of which converge in a point 3 on the axis of the generating wheel, The cone stmay be supposed to form a gear-wheel blank having its apexcoincident with the point to which the teeth of the generating wheel conx'erge. If the cone, while kept pressed against the generating Wheel 1., is .set in rolling motion around the same, the teeth 2 will'generate' impressions in the cone.- The shape of these impressions corresponds to the shape ofthe teeth 2, except that the side surfaces become curved. The contact between a tooth 2 and the cone 4 during the rolling movement of the latter always takes place along a line through the point 8, and the side surfaces of the teeth lie on a series'of straight radial lines all of which pass through the point 3.

If the'tops of theteeth of the generating wheel are out along aconical surface, the! top of Whichlies in the po1nt-3. and if the bottom surfaces of the gaps between the teeth constitute portions of the slde-surface of another conical surface, the top of which also lies in the point 3,- teeth of hitherto used shape will be generated on the cone 4 clurlng its rollingmovement on the generating wheel, the limlting surfaces of all gaps as Well as the top surfaces of the teeth converge if.extended,'in one and the same point. The tooth walls or surfaces generated by such generating wheel-will also lie on a seriesof straight radial lines converging on a point such as 3 in the manner mentioned above. easily'understood that the-tops of the teeth of the generating wheel may also 'be cut in any other manner wlthout interfering with the above described formation of the side surfaces of the teeth generated. Thus the teeth 2'mayfor instance be cut along a surface cutting the flanks of the teeth a long That is to say,

lines parallel to the top'lines of the teeth and consequently, parallel to each other.

he flattened as if they had been shaved ofi' evenly along their entire length.

In the practical manufacture of gearwheels according to the present invention,

the generating wheel may be substituted by an elongated cutting tool extending over the full length of the tooth andconveniently of the shape corresponding to that of atooth of the generatingwheel formed in cross-section 1n the abovelast mentioned a tooth of the generating wheel and the f cone 4, at the same time causing the cutting to the apex of the wedge.

1 addition, moves relatively to 'tool to make a cutting movement.

This is illustrated in Figs. 3 to 6fof the drawing in which 5 designates a gear-wheel. blank and 6 a tool shown diagrammatically. The latter may be composed of or form a series of cutting edges arranged 'one behind another, and its fundamental form constitutes a truncated Wedge having plane side surfaces and a planeparallel-sided surface near surfaces will interseet, each other, if extended, along the line 7-8 corresponding to the top or apex line of a tooth 2 of the generating wheell (Figs. 1 andZ). In order that the tool 6 during its cutting movement shall produce theoretically accurate flanks or side surfaces on the teeth, it is necessary, as will be easily evident from the above discussion concerning Figs. the tool always maintainssuch a position in relation to the gear-wheel j blank; that the supposed line '-78 always passes through the apexA of the pitch-cone of the gear-wheel blank and that the tool, in

blank in thesame manner as a tooth of the generating wheel 1 moves injrelation to the cone 4:. 1

According'to Fig. 3,'in which the direction of movement of the gear-wheel blank and of the tool (apart from the cutting movement of the latter) is indicated by the arrow a, the tool has cut into the gear-wheel It will, however, be

the tops of the teeth may This cutting tool and a gearduring the The two side teeth on different lines 1 and 2, that the gaps just described.

the gear-wheel.

blank so fan-that it has commenced to form one side (in the figure the right side) of the gap between two teeth. The surface so formed is shown in full lines and .is so formed as to lie on a series of straight lines such as the line 1(). This line which, as

will the other straight lines of the series,

indicates a temporary contact line between the tool and the gear-wheel blank, passes, if e endedfas will be evident from the foregoing description, through the point A. In. Fig t'the tool has reached a middle position relatively to the gear-wheel blank. The tool has. now, by means ofits right side according to the illustration, formed the right wall of the gap to such an extent, as is requisite for its engagement with a tooth of a goiiperating gear-wheel. The bottom of the gap, which in this" case willbe exactly or substantially of the same width throughout, is also edge of the tool has, to the left side of the bottom of the gap,- cut 'a comparatively finished, and the left sharply defined angular portion, which will the bottom of the gap, as the tool and the gear-duel blank continue their movement from'the middle position shown-in Fig. t

gap. Two different stages of this forming operation are shownin Figs. 5 and 6.

As is'evident from the above, it is possible, by means of a single tool and in the same working operation, to form both sides of the gap between two adjacent teeth, the gap having its sides formed on correct theoretical lines and the bottom located on a: conical or pyramidal surface, the top B of which, Fig. 4, lies above the apex of the pitch-cone, reckoning from the gear-wheel. In order. that two gear-wheels of the shape in question shall be'able to cooperate, it is 1 necessary to form the s'upper surfaces of the ployed,'so as toaccotnmodate them to the different angle of slope of the bottoms -of Thusthe tops will be out along a conical surface, thetop C of which, Fig. 4, is situated nearer to the gearwheel than the top of the pitch-cone.

.By such a formation of the teethian important advantage'is, however, attained, because the engagement of the teeth of two coacting gear-wheels commences at the outer ends of the teet-hand continues along longer and longer lines, until it extends finally along the whole length of the teeth. On account to those hitherto emformation of the left side of the gear willbe Of course, the invention is also applicable to bevel gear-wheels in which 'the teeth are inclined. relatively to radial planes through the axis of the gear-wheel, i. 6.,

skew or non radial teeth. Such a wheel is shown in Fig. 7 in side-view and plan. Also in this case each gapmay be out in a single working operation by means of the tool described above. In this case, however. the imaginary apex-line 7 8 ofthev tool has to touch a sphere, the center of which coinside surfaces and a lane top surface of the same width throug out, causing said tool to perform simultaneously 'a rolling and a cutting .movement in relation to the gearw'heel bl.ank,and causing the tool to maintain always such a position relatively to said blank, that the supposed top or apex line of the tool touches a, sphere having its center in the top of the pitch-cone and the radius of \vhichmay attain the limit value-:0;

2. A method of cutting bevel gear-wheels, consisting in formingthe space between each pair of adjacent teeth by means of an'elongated tool having a series of cutting edges placed one behind another, said tool being formed as a truncated wedge having straight pitch-cone and the radius of side surfaces and a plane top surface of the same width throughout, causing said tool to perform simultaneously a rolling and a cutting movement in relation to the gear-Wheel blank, causing the tool to traverse the blank .once in cutting each said space and forming theadja'cent side surfaces of the said teeth, and causing the tool to maintain always such a position relatively to said blank, that the supposed top or apex line of the tool touches a sphere having its center in the top Of the which mayattain the-limit value- 0.

3. A method of cutting bevel gear wheels, I

consisting in forming the space bet een each pair of adjacent teeth by means or a cutting tool formed as a truncated wedge having straight. side surfaces and a plane top surface, causing said tool to perform simultaneously 'a' rolling and a cutting movement in relation to the gear wheel blank, and

causing the'tool to maintain always such a position relatively'to said blank, that the supposed top or apex line of the tool touches a sphere having its center in the top of the pitch cone and the radius of which may attain the limit value-:0, whereby the bottoms of the spaces coincide with a cone intersecting the normal pitch cone and having its apex farther removed from the gear.

In testimony whereof I have hereunto, set my hand in presence of two subscribing witnesses.

ERIK HJALMAR WINGQVIST.

Witnesses:

THUN S. Fowler,- KARL Runosnoo. 

